The present invention is concerned with a control device for recording elements for data which are part of a given aggregate of data recordable by each of these elements.
It is known that for the purpose of fast recording it is useful to have apparatus available which comprises a large number of recording elements, controlled consecutively or simultaneously. One of the methods, generally in use, for the control of such recording apparatus is to compare the data to be recorded with the data which the elements are capable of recording at given instants. The control devices of these recording apparatus perform comparisons between, on the one hand, coded data to be recorded and, on the other hand, coded data which is able to be recorded. When two data of these aggregates are identical, the control device sends a signal to the recording element which is to carry out the recording. One type of recording apparatus controlled by devices of this type which may be mentioned, for example, are printing machines connected to computers, such as the so called "on-the-fly" printers. This term refers to the fact that the impression is performed by the striking of hammers on characters that have a mobile support. In the case of wheel printers, the support consists of several identical sets of characters arranged in circles round the wheel. In the case of printers with a linear support the identical sets follow each other consecutively. In spite of comparable performances, from the viewpoint of speed of impression, the use of printers with a linear support is often preferred because of the quality of the impression through the affiliated control device is more complex. In the wheel printers the different sets of characters may be placed in such a manner that the same repeated character may at a given moment be positioned opposite any hammer. This is not so in the case of the printers with a linear support where, irrespective of the arrangement of the characters on the support, an order of character sequence occurs in front of the hammers which depends on the respective positions of the latter. This case results in a greater complexity of the control device, basically due to the important role of the storage media for the coded characters which each of the hammers may hit as a function of the time and of the address curcuit which is connected with these storage media.
These media usually consist of a memory of relatively large capacity since it must contain all the sequences of coded characters that each hammer may strike during the imprint of a line on paper. Each of the coded characters of each of these sequences must be compared with the data to be printed coded in the same manner. This explains, on the one hand, why the construction of such a control device is sensitive and cumbersome, and on the other hand, why its operation is limited as far as speed is concerned.
One of the objects of the present invention is the simplification of the storage media for recordable data by each of the recording elements as well as simplification of the media of storage for the data to be recorded.